Note for Analog Electronic Circuits - AEC by Abhishek Kumar

Topics ( 12 )

Text from page-1

Syllabus F.Y.B.Sc. (IT) Electronics and Communication Technology Unit I : Concept of Conductor, Senmiconductor, Insulator, Semiconductor Diode, Forward bias, Reverse Bias, Application of Diode as Rectifier, Zener diode and its applications, Introduction to Transistor (BJP, FET), PNP, NPN Transistors their Characteristic. Application to Transistor as amplifier and as a Switch. Unit II : Concept of amplification, amplifier notations, Av, Ai, Ap Zi, Zo), Application of BJT as single stage Amplifier, Frequency response of single stage Amplifier. Multistage Amplifiers :- (Basics concepts) RC coupled, cascade, Darlington pair, DC amplifier. Unit III : Concept of Feeback :- Negative Feedback and its advantage in Amplification, Positive Feedback :- Oscillators, RC Phase Shift Oscillator, LC Oscillator, Switching Circuits Multivibrators :- Monostable using IC 555 and Astable using IC 555 (including problems) Unit IV : Introduction :- Need for modulation system, Concept of Modulation. AM, Definition of AM, Modulation index, Power relation in AM, Generation, Demodulation of AM. SSB :Power requirement in comparison with AM, Advantages of SSB over AM, Concept of Balanced Modulator, Generation SSB, Pilot Carrier System, Independent Side System, Vestigial Sideback Transmission. Unit V : FM :- Definition of FM, Bandwidth, Noise triangle, Per-emphasis and De- emphasis. PM :- Definition of PM. Difference between AM and FM. Radio receivers. Pulse Modulation :- Sampling Theorem, PAM, PTM, PWM, PP. pulse code modulation, Quantization noise, companding, PCM system differential PCM, Delta modulation. Multiplexing :- FDM/ TDM. Television Scanning, Composite Video Signal, Television Transmitter, Television receiver. Unit VI : Introduction to Digital Communication : PSK, ASK, FSK. Introduction to fibre optics system : Propagation of light in optical fibre; Types of fibre : Single mode, steps index. Graded index, Signal distortion: attenuation, dispersion, Optical sources : LED, LASETS. Optics Detectors and optics links. Link Budget. References : Allen Mottershead, ―Electronic Devices and Circuits‖, PHI Boylstead and Neshelesky, ―Electronics Devices and Circuits‖, 4th, PHI, 1999. Simon Haykin, ―An Introduction to Analog and Digital communications‖, John Siley and Sons. R.B. Carlson, ―Communication System‖, MacGraw Hill. George Kennedy, ―Electrical Communication Systems‖, Tata McGraw Hill 1993. Roody Collin, ―Electronics Communication‖, PHI J. Millman and A Grabel, ―Microelectronics‖ MacGraw Hillm, 1998. Proakis J.J., ―Digital Communications‖ McGraw Hill.

Text from page-2

Digital Communications by TAUB Schilling Electronic Communication Systems, Roy Blake Delmar, Thompson Learning Introduction to telecommunications, Anu A Gokhale, Delmar Thompson Learning Term Work and tutorial Should contain 5 assignments and two class tests Practical : Should contain minimum 8 experiments. List of Practicals : 1. Study of Zener diode characteristics 2. Study of Half wave and full wave rectifiers 3. Study of bridge rectifier 4. Study of Transistor as a switch 5. Monostable multivibrator using IC 555 timer 6. Astable multivibrator using CI 555 timer 7. Study of Wien bridge oscillator 8. Frequency Response of single transistor amplifier 9. Study of Amplitude Modulation 10. Study of Frequency Modulation 11. Study of Fibre Optic transmission 12. Study of Pulse Amplitude Modulation 13. Study of transistor DC Amplifier 

Text from page-3

UNIT I SEMICONDUCTOR DEVICES 1 SEMICONDUCTOR ELECTRONICS PART ( I) Unit structure : 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 Objectives Introduction Classification in solids Types of semiconductors p-n junction diode Forward and reverse bias junctions Advantages of semiconductors Junction diode ad rectifier Volt ampere characteristics of a pn junction Zener diode Summary Unit end exercise 1.0 OBJECTIVE : In this lesson we are focussing mainly on the semiconductors. The conduction phenomenon in semiconductors. Their uses and different applications in electronics such as applications of diodes as rectifiers , Zener diode and its use as regulator. 1.1 INTRODUCTION : A solid is a large collection of atoms. The energy levels of an atom get modified due to the presence of other surrounding atoms and the energy levels in the outermost shells of all the atoms form valence band and the conduction band separated by a forbidden energy gap. The energy band formed by a series of energy levels containing valence electrons is called valence band. At 0 K, the electrons start filling the energy levels in valence band starting from the lowest one. The highest energy level, which an electron can occupy in the valence band at 0 K, is called Fermi level. The lowest unfilled energy band formed just above the valence band is called conduction band. At 0 K, the Fermi level as well as all the lower energy levels are completely occupied by the electrons. As the temperature rises, the electrons absorb energy and get excited. The excited electrons jump to the higher energy levels. These electrons in the higher energy levels are comparatively at larger distances from

Text from page-4

the nucleus and are more free as compared to the electrons in the lower energy levels. Depending upon the energy gap between valence band and the conduction band, the solids behave as conductors, insulators and semiconductors. 1.2 CLASSIFICATIONS IN SOLIDS We know that some solids are good conductors of electricity while others are insulators. There is an intermediate class of semiconductors. The difference in the behaviour of solids as regards electrical conductivity can be beautifully explained in terms of energy bands. The electrons in lower energy band are tightly bound to the nucleus and play no part in the conduction process. However the valence and conduction bands are of particular importance in ascertaining the behaviour of various solids. 1.2.1 Metals ( Conductors ) : Conductors (e.g. copper, aluminium) are those substances which easily allow the passage of electric current through them. It is because there are a large number of free electrons available in a conductor. In terms of energy band, the valance and conduction bands overlap each other as shown in Fig. 1.1. Due to this overlapping, a slight potential difference across a conductor causes the free electrons to constitute electric current. Thus the electrical behaviour of conductors can be satisfactorily explained by the band energy theory of solids. For example, (i) in sodium, the conduction band is partially filled, while the valence band is completely filled. (ii) The valence band is completely filled and the conduction band is empty but the two overlap each other. Zinc is an example of band overlap metals. CONDUCTION BAND OVERLAPPING OF BANDS VALANCE BAND Fig. 1.1 Energy Bands in Metals (Conductors) In both the situations, it can be assumed that there is a single energy band, which is partially filled. Therefore, on applying even a small electric field, the metals conduct electricity.